diff options
Diffstat (limited to 'kernel/arch/avr32/boot/u-boot/head.S')
| -rw-r--r-- | kernel/arch/avr32/boot/u-boot/head.S | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/kernel/arch/avr32/boot/u-boot/head.S b/kernel/arch/avr32/boot/u-boot/head.S new file mode 100644 index 000000000..2ffc298f0 --- /dev/null +++ b/kernel/arch/avr32/boot/u-boot/head.S @@ -0,0 +1,83 @@ +/* + * Startup code for use with the u-boot bootloader. + * + * Copyright (C) 2004-2006 Atmel Corporation + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ +#include <asm/setup.h> +#include <asm/thread_info.h> +#include <asm/sysreg.h> + + /* + * The kernel is loaded where we want it to be and all caches + * have just been flushed. We get two parameters from u-boot: + * + * r12 contains a magic number (ATAG_MAGIC) + * r11 points to a tag table providing information about + * the system. + */ + .section .init.text,"ax" + .global _start +_start: + /* Initialize .bss */ + lddpc r2, bss_start_addr + lddpc r3, end_addr + mov r0, 0 + mov r1, 0 +1: st.d r2++, r0 + cp r2, r3 + brlo 1b + + /* Initialize status register */ + lddpc r0, init_sr + mtsr SYSREG_SR, r0 + + /* Set initial stack pointer */ + lddpc sp, stack_addr + sub sp, -THREAD_SIZE + +#ifdef CONFIG_FRAME_POINTER + /* Mark last stack frame */ + mov lr, 0 + mov r7, 0 +#endif + + /* Check if the boot loader actually provided a tag table */ + lddpc r0, magic_number + cp.w r12, r0 + brne no_tag_table + + /* + * Save the tag table address for later use. This must be done + * _after_ .bss has been initialized... + */ + lddpc r0, tag_table_addr + st.w r0[0], r11 + + /* Jump to loader-independent setup code */ + rjmp kernel_entry + + .align 2 +magic_number: + .long ATAG_MAGIC +tag_table_addr: + .long bootloader_tags +bss_start_addr: + .long __bss_start +end_addr: + .long _end +init_sr: + .long 0x007f0000 /* Supervisor mode, everything masked */ +stack_addr: + .long init_thread_union +panic_addr: + .long panic + +no_tag_table: + sub r12, pc, (. - 2f) + /* branch to panic() which can be far away with that construct */ + lddpc pc, panic_addr +2: .asciz "Boot loader didn't provide correct magic number\n" |